The present disclosure relates to an image forming unit and an image forming apparatus with the same and particularly relates to a mechanism for pressing a process roller against an object and drawing it back from the object.
An electrophotographic image forming apparatus forms an image by electrically charging the surface of a photosensitive drum at a nip with a charging roller, subjecting the charged surface of the photosensitive drum to light exposure and development to form a toner image, transferring the toner image to a recording paper sheet, and fixing it on the recording paper sheet. Despite recent demands for longer product life, in the image forming apparatus having the above structure, deterioration of the charging roller due to contamination may cause reduced product life.
To cope with the above problem, a mechanism is proposed for preventing contamination of the charging roller by forming a nip between the charging roller and a cleaning roller formed of a foamed roller and cleaning the charging roller with the cleaning roller. However, if the cleaning roller or the charging roller is permanently deformed by pressure imposed thereon by the nip formation, abnormal charging will occur to have adverse effects on an image to be formed. Therefore, a technique is proposed in which the rollers to be placed under pressure during nip formation are moved away from each other to release them from the pressure and thus avoid their permanent deformation.